
\begingroup
\centering
\begin{tabular}{lcccccc}
   \toprule
    & \multicolumn{2}{c}{Ammonia} & \multicolumn{2}{c}{Total Kjedahl Nitrogen} & \multicolumn{2}{c}{Phosphorus}\\
                           & (1)            & (2)            & (3)            & (4)            & (5)          & (6)\\  
   \midrule 
   ATT                     & -0.079$^{***}$ & -0.078$^{***}$ & -0.206$^{***}$ & -0.194$^{***}$ & 0.039$^{**}$ & 0.024$^{*}$\\   
                           & (0.025)        & (0.025)        & (0.063)        & (0.065)        & (0.016)      & (0.012)\\   
    \\
   \# HUC12                & 299            & 299            & 178            & 178            & 240          & 240\\  
   Dependent variable mean & 0.13459        & 0.13459        & 0.54119        & 0.54119        & 0.15552      & 0.15552\\  
   Observations            & 13,756         & 13,756         & 2,953          & 2,953          & 8,579        & 8,579\\  
   Adjusted R$^2$          & 0.37473        & 0.36960        & 0.48264        & 0.48042        & 0.40709      & 0.37710\\  
   \bottomrule
\end{tabular}
\par\endgroup


